ARLINGTON, Texas — For Jon Lester, it’s not about how high-wattage his pitching matchup Sunday against Texas Rangers ace Yu Darvish will be. It’s about how few and far between the runs will inevitably be.

Darvish, the 26-year-old pitcher that the Texas Rangers invested more than $111 million into a year ago, will be on the other side.

So will his 5-1 record, his 2.33 ERA, his major league-leading 58 strikeouts, the array of pitches he has on a string, and the center-of-the-universe pull he currently has on the baseball world.

Lester knows it will be a battle.

“With a guy like him . . . there’s probably not going to be a lot of runs scored on him tomorrow,’’ he said.

“So you just know that going in. You’ve got to be a little more careful in those situations. So that’s really it. You’ve got to bear down a little bit, I wouldn’t say more than normal, but a little bit more than normal, I guess.’’

As focused as he is, Lester keeps his eyes out for whichever game happens to be on the clubhouse television. He keeps his ears open to hear the word on whichever player his teammates are buzzing about. He was fully aware of Yu’s near no-hitter a month ago.

“I’m a baseball fan,” Lester said. “I like to pay attention as well.”

Lester is off to a 4-0 start, rediscovering the form that made him one of the more dominant lefties in the American League.

“The biggest thing for me is just getting back to being me,” Lester said. “Obviously, the change in mechanics helped. Getting back to that good position and getting my arm back online and being able to get my cutter back into righties with some depth, that’s been the biggest thing for me. Just those little adjustments and I think it’s helped put me in a good position.”

Still, Darvish has been a marvel for the Rangers. His performances have turned teammates into on-field fans at times.

“He’s really good, man,” said Rangers second baseman Ian Kinsler. “He does things that a lot of guys can’t do on the field. So when he’s on the mound, you expect something special.”

The leaps Darvish has made in a year’s time is what impressed Sox outfielder Mike Carp.

A year ago, as a Seattle Mariner, Carp saw two very different Darvishes. The first encounter was a late-May matchup in Seattle. Carp went 0 for 2, but watching Darvish walk six and give up five runs on four hits over four innings, he left unimpressed.

“It didn’t seem like he was overwhelming,” Carp said.

When they faced each other again four months later in Arlington, Darvish was dominant. Over seven innings of one-run, two-hit ball, Darvish struck out nine Mariners, including Carp twice.

“He definitely had it all together,” Carp said. “He was mixing all his pitches, changing speeds and still throwing it 95 if he wanted to. He was definitely just a different type of pitcher.”

The consistency built over the course of last season has carried over to this year. He’s throwing more pitches per plate appearance by a hair (4.13 this season, 3.87 last season), but that’s partially because he’s getting more swinging strikes (29 percent) and fewer hitters are making contact (59 percent).

“He definitely learned a lot last year throughout the season and was able to improve and, I think, take his experiences into the offseason and focus on the things that were going to make him more consistent,” Kinsler said. “That’s what he’s done this year so far. He’s become more consistent, kept his pitch count down, and he’s been really effective. So we basically expect more of the same from him.”

Sox manager John Farrell said the same of Lester.

“We know that Yu is good, but I’m looking forward to Jon Lester going back out and pitching like he has for four of the six starts that he’s made for us,” Farrell said. “That’s where my focus is.”